The invention relates to solar collectors and, specifically a frame or carrier element therefor, having a rigid-cellular plastic filling body completely or partially formed with a tight-sealing synthetic top layer, and to a process for the manufacture thereof.
It has been known to mold synthetic parts, specifically carrier inserts for solar collectors see German patent publication (DOS 2,510,321.) These synthetic manufactured inserts are mounted within metallic frame casings and serve to stack any required booster components such as solar collectors and glass, masking frames, etc., according to their end-use. The synthetics used for such inserts may be of a rigid-cellular plastics type as described in German patent application (DOS 2,532,174 or German utility Pat. No. 7,630,194.) Inserts such as these are used as non-lead bearing components in metal casings, and serve for reinforcement and attachment purposes as described in German utility Pat. No. 7,624,195.
The known metallic casings require the use of these synthetic inserts to provide the thermal damping or insulation of applied solar-radiated heat because the metal itself--based on its high thermal conductivity--would pass on the solar-radiated heat to the environment to an almost undiminished degree. On the other hand, the known synthetic inserts are insufficient to provide the strength, rigidity, and ruggedness necessary to outdoor use. Because of the extensive tooling required in their production, the manufacture of known metal casings is expensive; furthermore, their weight is too high for customary roof designs. They represent detrimentally effective thermal bridges, and their assembly is expensive. Casings made of rigid-cellular plastics alone on the other hand do not meet the requirements occasioned by their special use. Casings used as solar collectors are exposed to considerable temperature fluctuations and constantly varying environmentally produced damaging effects. It must be taken into account that carrier frames for solar collectors such as these are used alike in regions having a moderate climate and those of subtropical climate, where they are exposed to high humidity and enormous solar radiation levels. Additionally, carrier frames such as these must resist jolts and impacts caused by their mounting and/or transport.
Generally known molded parts may have a core of rigid cellular plastic, which is completely or partially coated with a tight-sealing protective layer (see German patent publication DOS 2,506,414.) The protective layer serves to give the molded part an optically attractive appearance by being more scratch resistant or more suitable for lacquer coating than just a rigid cellular plastic body. Molded parts such as these should not be exposed, however, to extreme weather conditions, specifically rough temperature fluctuations, because this may lead among other effects to a rapid peeling off of these layers.
The object of the invention is to produce a molded part, specifically a carrier frame for solar collectors, which has a low weight and good insulator property as well as a long rated service life despite multi-use conditions and environmental effects, and which can be simply handled and inexpensively manufactured.